sample, C++ (gcc) - rextester

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//g++  4.9.3

#include <iostream>

class Cars {
public:
    bool operator==(Cars &right);
    Cars &operator=(Cars &right);
    virtual double Score() = 0;
    virtual void Print() = 0;
    virtual ~Cars(){};
};

class Sedan :public Cars {
public:
    Sedan();
    Sedan(int cost, float road_clearance);
    Sedan(std::istream& is1, std::istream& is2);
    Sedan(const Sedan &orig);
    double Score();
    int Cost();
    int Speed();
    void Print();
    Sedan &operator=(Sedan &right);
    friend Sedan operator +(const Sedan &left, const Sedan &right);
    friend std::istream& operator>>(std::istream& is, Sedan &Sedan);
    friend std::ostream& operator<<(std::ostream &os, const Sedan &obj);
    ~Sedan();
 
private:
    int cost;
    int speed;
};

void Sedan::Print() {
    std::cout << "S:" << cost << ", " << speed << std::endl;
}

class TQueueItem {
public:
    TQueueItem();
    TQueueItem(Cars& car);
    TQueueItem(TQueueItem& orig);
    friend std::ostream& operator<<(std::ostream& os, const TQueueItem& obj);
    
    TQueueItem *GetNext();
    Cars *GetCar() const ;
    ~TQueueItem();
    TQueueItem *next;
private:
    Cars *car;
};

class TQueue {
public:
    TQueue();
    TQueue(const TQueue &orig);
 
    TQueue(Cars &car);
    int GetSize();
    void PushBack(Cars &car);
    void PushBack(Cars *car); 
    Cars *PopFront();
    bool Empty();
    friend std::ostream& operator<<(std::ostream &os, const TQueue &queue);
    
    void ISize();
    void DSize();
    
    ~TQueue();
    
private:
    TQueueItem *head;
    TQueueItem *tail;
 
    int size;   
};

void TQueue::PushBack(Cars &car) {
    TQueueItem *item = new TQueueItem(car);
    item->next = nullptr;
    tail->next = item;
    tail = item;
    tail->GetCar()->Print();//здесь все правильно выводится
    delete item;
    size++;
}

std::ostream& operator<<(std::ostream &os, const TQueue &queue) {
    //if (queue.size != 0) {
    std::cout << "in print" << std::endl;
    TQueueItem *ptr = queue.head;
    while (ptr != nullptr) {
        os << (*ptr) << std::endl; //если здесь ptr->GetCar()->Print(), то тоже virtual function call
        ptr = ptr->GetNext();
    }
    return os;
}

std::ostream &operator<<(std::ostream& os, const TQueueItem &obj) {
    os << "[";
    obj.GetCar()->Print();//virtual function call
    os<< "] ";
    return os;
}

int main()
{
    std::cout << "Hello, world!\n";
}

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Compilation time: 0.32 sec, absolute service time: 0,5 sec